Ion mobility spectrometers (IMS) have become a common tool for detecting trace amounts of chemical and/or biological molecules. Compared to other spectrometric chemical analysis technologies, e.g., mass spectrometry, IMS is a relatively low resolution technique. The IMS advantages of very high sensitivity, small size, low power consumption, and ambient pressure operation are in some cases completely offset, or at a minimum, reduced by the lack of sufficient resolution to prevent unwanted responses to interfering chemical and/or biological molecules. The false positives that result can range from minor nuisances in some scenarios to major headaches in others. Interfering chemical and/or biological molecules can have very similar ion mobilities which in turn can significantly limit detecting and identifying low levels of the targeted chemical and/or biological molecules in the sample.
Another IMS resolution issue can occur as the molecules increase in molecular complexity (size, number of stereogenic centers, number of chiral centers, number of functional groups, etc). More conformations are possible due to the flexibility of the molecule, which can thus adopt multiple different conformations while traveling down the drift tube.
The present state of the art ion mobility spectrometers lack the ability to: directly reduce the occurrence of interfering chemical and/or biological molecules in a sample's analysis, limit the number of possible conformations of a molecule, and report the relative difference of a molecule to an internal standard. The molecular geometry of molecules can be utilized in the efforts to explore new analytical spectroscopic/spectrometric techniques. It is the purpose of this invention to overcome these obstacles by making the use of a molecule's molecular geometry. A chemical modifier and/or a shifting reagent can be used to reduce the occurrence of interfering chemical and/or biological molecules in a sample's analysis. Differentiating components in a sample in an IMS can be done by utilizing at least one additional property of the components besides their ion mobility and/or ion mobility differences. Adding energy to the components of the sample to be separated can enhance separation in IMS.